Vehicle with pneumatic support



Feb. 23, 1965 K. J. FEwr-:L ETAL 3970533 VEHICLE WITH PNEUMATIC SUPPORT Filed July 5, 196s e sheets-sheet 1 AGENT Feb. 23, 1965 K. J. FEWEL ETAL 3,179533 VEHICLE WITH PNEUMATIC SUPPORT Filed July 5, 1965 G Sheets-Sheet 2 I8 l l HMKENNETH. J. FEWEL l2 GENE F. SCHELL I3 FIG |4 BYRON R. w/NBoRN INVENTORS.

BY Jak- AGENT Feb. 23, 1965 K. J. FEWEL ETAL.

VEHICLE WITH PNEUMATIC SUPPORT 6 Sheets-Sheet 3 Filed July 5. 1965 KENNETH J. FEWEL GENE P SCHELL BYRON R. W/NBORN INVENTORS AGENT FIG. s

FIG. 5

Feb. 23, w65

K. J. FEWEL ETAL VEHICLE WITH PNEUMATIC SUPPORT 6 Sheets-Sheet 4 Filed July 5, 1965 L E NS. W RR EL00 FHWT HMM Hx .V T RW. EPN www E Y K Y B AGENT FIG. 9

Feb. ,23, 1.965 KJ. FEwEL ETAL VEHICLE WITH PNEUMATI'C SUPPORT 6 Sheets-Sheet 5 Filed July 15, 1965 KENNETH J. FEWEL GENE E' SCHELL BYRON R. W/NBORN INVENTORS BY fic RZQM FIG. ll

AGENT Feb. 23, 1965 K. J. FEwEL ErAL 3,170,533

kVEHICLE) WITH PNEUMATIC SUPPORT Filed July 5, 1963 6 Sheets-Sheet 6 KENNETH J- FEWEL GENE l? SCHELL BYRON R. WINBORN INVENTORS.

AGENTI United States Patent 3,170,533 VEHICLE WITH PNEUMATIC SUPPORT Kenneth J. Fewel, Arlington, and Gene P. S'chell and Byron R. Winborn, Irving, Tex., assignors to Ling- Temco-Vought, Inc., Dallas, Tex., a corporation of Delaware Filed July 5, 1963, Ser. No'. 292,984 21 Claims. (Cl. 180-9.2)

This invention relates -to a continuous track vehicle and more particularly to a vehicle with pneumatic support.

The accommodation of vehicles to various types of terrain encountered in exploration of or in travel through undeveloped areas in general is diicult because of the wide variety'of environments encountered. Amphibious vehicles, swamp buggies, and crawlersof various types are known. The present invention is directed to improvements over such vehicles and yspecifically to a vehicle with support by pneumatic cushions between the vehicle and its endless, belt-like treads.

It is an object of the present invention to provide a vehicle having a pneumatic tread in which the tread itself is in supporting relation to the vehicle and spaced from the same by a pneumatic chamber. It is -a further object of the invention to provide a construction in an endless, belt-like tre-ad having inflated cells and a lower-surface bearing course extending between wheels or rollers wherein localized distortions which may occur in the bearing course Vare accompanied by no more than quite small pressure gradients between cells of the tread. Another object is to provide for damping to prevent or minimize bounding of the vehicle. A stillfurther object is to provide for the replacement of air lost in consequence of the puncture of any given cell. Yet another object of the invention is to provide for isolation of -a given cell when air loss exceeds a predetermined rate.

For a more complete understanding of the present invention and for further objects and advantages thereof, reference may now be had to the following description taken in conjunction with the accompanyingdrawing in which:

FIGURE 1 is a front View of an embodiment of the present invention;

FIGURE 2 is a left side View of the vehicle of FIG- URE 1 with the skirt partially removed;

t 3,170,533 Patented Feb. 23, 1965 ice 2 able characteristics of prior art vehicles.Y The vehicle may operate in swamps, marine areas, tundra, muskeg, and `other environments encountered throughout the `world. The invention will be described in connection p endless treads and 11 which extend along the sides of vFIGURE 3 is a top view of the vehicle of FIGURES FIGURE 4 is a detailed sectional view of -a portion of l a-trcad;

FIGURES 5 and 6 diagrammatically illustrate the effects of variations in tread geometry;

FIGURE 7 is a fragmentary sectional view taken along v,

the vehicle and which Iare characterized by bulky, vmulticell, laterally extending chambers. The chambers are low-pressure units which cushion the Vvehicle and envelope obstacles over which the vehicle travels. As seen in FIGURE 2, the lefthand tread 10 is supported by a pair of wheels 14 and 15 mounted lfor rotation on axles 16 and 17 respectively. Axles 16 and 17 are journaled in a frame 23 comprising an elongated, ovaleshaped side skirt 20 and a fender 21 extending over the upper course of the tread 1l). p y f VAsshown in FIGURE 3, the `frame 23 has a central, cargo-carrying bay 29. A drive engine 160 (FIGURE .1), is positioned -a't the front below the floor of -a cab 25. The usual vehicle controls are provided, including a steering wheel 26. Included are a forward-facing drivers seat 27 (FIGURE 3) and passengers seat 28. The cargo space 29 i-s closed by a hingedtail gate 30 to form a compartmentsuitable for varied uses. As illustrated, the vehicle is ttcd for carrying personnel by the inclusion of benches 31 and 32. f

It is evident from FIGURE 3 that a substantial portion of the are-a covered by the vehicle is occupied by the tread system. Treads of such area provide extensive ground contact along the entire length of the lower cour-se thereof, and the load per unit area at any point along the con-k tact surface is thus maintained at a minimum. Low-pressure cells with provision for limited interchange of4 air between cells, -as will be described, permit operation over rough terrain with minimum vertical movement of the body; further, the low cell pressure permits travel over objects wi-th reduced vulnerability to puncture.v Most courses over natural hazards may be negotiated without damage to the cell system. t l Tread 10 (FIGURE 2) includes a plurality of transverse cells mounted on an endless belt 40 which passes over roller-like wheels 14y andr15 that serve as pulleys and have cylindrical surfaces :for support of the continuous tread 10. The vehicle is supported on tread 10along the lower course of the latter extending between wheels `14 and 15, by air maintained under pressure inv adownwardly facing plenum chamber 33 substantially closed at the bottom by the belt- 40 yand at the'ends by wheels 14, 15' and suitable variable closures 34 and 35. As will be seen, theplenum top wall or bulkhead 36 is secured to the frame 23 so that prim-airy support oct? the vehicle isy 1 by way'of an air cushion maintained in the plenum 33.

t yFIGURE l1 is a schematic, top, sectional view showing t;

FIGURE 14 isa semi-diagrammatic, sectionalA View of a form of the cell isolating means.

The present invention is directed to a vehicle, a tread system, land a Vdrive therefor to provide pneumaticV supportl for a vehicle which is free from many of the undesir- The two' layers of cells on the belt 40 and-the plenum chamber 33 ltogether prowidetthree'stages of pneumatic cushions effective in support of the weight of the vehicle.

The flexible belt 40 (FIGURES 2 and 4) is of awidth corresponding to the width of wheels 14 and 15; of length adequate to encompass the wheels 14 and 15, the belt has two layers of transversely extending cells `secured* thereto. -A iirst or inner .set of cells, such as the cells -41 and y43', are positioned on 4the periphery or face'of belt 40. Cells 41 and 43 of the inner layer are live-sided tubes with parallel, planar ends.

Inner cell 41, for example, has one side wall contiguous to a sidewall of the adjacent cell 44 in an outer layer of pneumatic A cells. Inner cell 43 and outer cell 44 similarly have contiguous walls. Outer g cells 45 and 46 areimmediately adjacent -to outer cell ,44;

entire `length ofV the belt 40.-v Contiguous outer cel-ls, f

for example the outer cells 44 and 46, are hinged together as by a hinge pin 47 attheir common juncture. Each outer cell, for example cell 44,*is secured to a respective belt cleat, described below, by a hinge pin 42.

.The flexible construction of thecells and :their geometry provide for Apassage of the tread around wheels 14. and with a minimum Vchange of volume even thoughit is necessary that their shape be substantially altered. The transition from a straight courseto an Aarcuate course defined bythe wheel periphery is smooth, thus minimiz-V ingjloadin'gs induced by centrifugal accelerations and abrupt variations of internal .pressure during the transition. Y

- Referring now to FIGURE 4, belt 40 is a fabric-reinforced, rubbe'r-covered transmission belt of wellknown construction. As"mentifonedr,rthe cells of the outerv layer are fastened to belt 4i) by meansv of cleats such as the cleat Si). Each cleat Sil'is made of vrubber reinforced with cord orv fabric and vulcanized to vthe surface of the belt Y 4@ -to form a structure of triangulary cross-section and extending'the width of the belt. Tov attach itto a respective cleat 50, each cell 44 is provided, at its juncture with the cleat, with a rib formed the manner of a piano hinge l1alf.` A-similar rib is formed on the cleat Silandthe two ribs are locked together by the hinge rod '42, which preferably is made of a tough, flexible material such as nylon. Cells 45 and 46 are similarly ,coupledl together by the hinge pin or rod 47V. f y

' {Reinforcing' fabric layers 53 and 54 `are vulcanized into placeoneach end of each inner cell as shown in cell 43; sandwiched between thefabric layers are stays such as stay 56." The stays 56 ateach end of each inner cell are connectedat their centers bya cable 55, preferably made ofik steel,l which minimizes ballooning of the inner cell such-as 43at its ends. Similarly, the kends of each outer cell Vsuclias 46l are covered with superimposed layers of reinforcingy fabric 5'7 vulcanized in placeandcontaining between them an annular stay S8. Prefeablythree cables et), 61, extend between and connect the stays 58`Vin each end'fof each outer cell such as 46 to prevent bal,-

other. The series coupling, iuustrated'in'rrounn 4, is

preferable because it can be housed completely'within the treadv and requires a minimum of` structure', it will be'appreciated, however, that a parallel manifolding system alternatively -may be employed for interchange of air betweenthe cells. .The opening formed by each oriice structure tube such as 63 is large enough to minimize shocks to the vehicle by permitting auv adequate .airflow between ccllswhen an. outer cell rapidly passes onto and -er'igulfsl a large object but small `enoughto'prevent substantiallyfree vairliow'be'tweenV cellsrandV thus to damp out the long-period bounding of thegvehicle which otherwise could occur. Y y

' The three-"stagsuspension provided by theplenum and by `the two layers of cells results infad'vantages including smooth, shock-free riding qualities and uniform distribution'of ground loading forces. Not only` an outer cell is deformable upon impinging upon and enguliing an object; oneY or more inner cells'are compressible, and the belt is deflectable into the plenum chamber in response to the locally imposed yincrease inload. Becauseof the mechanical and iiuid connections lbetween them, moreover, Ithislocal increase in load is` widely distributed, `with the resultV that Yground loading, from cell to cell, is quite uniform. c

It hasbeen found desirable to limit the flow coupling, asrepresented'by .tubes 64, 66, to a limited number of compartments formed by sub-groups of cells. For example, from five to seven cells may be operated as aV Y single, interconnected unit or multicell chamber. At

two or more places,the ports in adjacent wallsforming the boundary' ybetween one multi-cell chamber andthe vsub-grouping-of cells. provides a measure of control over the period of oscillation of the suspension and permits looning of the cell end walls. For convenience of illus- 'f tration, the stays of only Vthefinnerv cell 43 and outer cell shapes indicated' in the drawing.V Built-up exterior sur- Vface Aconfigurations may beprovided on the exterior surfaces of the outer cellss'uch as cell46 toenhance trac? tion, in sand, snow, water, or the like.. Y

As shown in- FIGURE 4, provisions are included `fo damping and minimizing the bounding which heretofore has .characterized large, pneumatically supported vehicles. Inner cell 43 includes agpair of, short, flanged tubes 63 amd64, the lflanges on the tubes being vulcanized to the walls of cell '4f-3. Cell 4 6 is providedwith a'reinforced orifice structure `e'fwhich sealingly mates with the exterior wallsurface of tube 63; Similarly, tube. 6'4 is en'- cornpassed byandsealed tothe wallofa reinforced orifice structure 66 .inthe wall of cell 44.., The; passages thus formed'l interconnect the adjacent,V interleaved cells 43, .44,

airbut alsogtoanchor the inner-layericell't Vin its desired position. Thus, air 4mayflow through'the cell sys-Y without assuming a disproportionate share. ofthev load Vand continuous, though limited, operation even thoughcells of a given4 sub-group are damaged by severe rupture. With the cells divided into subegroups, the entire track will not bedeflatedI in the event of a'leak or even a severe rupture that requires the vehicle tobe stopped and a cell orcells replaced. ,'IfY all cellsbecame deflated, the( vehicle would develop la Asevere list,;and it will be appreciated thatV cell replacement is much easier where, as, withsub-grouping..

of cells, ythe vehiclel may` be rolled 'to a Vposition inrwhichV it is held level by normally functioning` cells Yandin which they cell to be vreplaced lies l course ofthetrack.. In a preferredembodiment` of the invention, the cleats Sil and the inner and Aouter'cells suchas cells 43, 44. are

of such dimensions thatthereiis aminimumchange in volume of any of the cells inkpassingfrom afstraight amuser to,v the arcuatecourses Yaroundjthesupporting wheels. 'l The ejlfectfof variationsin relative dimensions ofl the Vcleats And the cells is readily apparentfrom inspec- Y. non er FIGURES 2, 5, andy 6.

`In FIGURE 5', itwill be notedv that relatively. large r cleatsy suchfas .89.. and182 are secured .tothe belt 40'.- With 'and 46 and serve not only to provideforinterchangeiof without any great internal pressure increase. VAtV the same gtime forces; appliedv to` thetread which otherwise would cause bounding are damped by air flow from one` cellto another.V Thecell sysem thus forms a series-type cleats of this size,v the ratio of the radius ofthe outer-cell hinge poil-'11:81 to the radius of thepeaks of cleats 8i? and n 82 is relativelysmall. As a result, outer cell 83 is radicali `ly deformed in. passing around the wheelrll4,.and apsub-V stantial decrease cell 83. In FIGURE.

irrthe'volurne isv experienced in outer creases in volume.v

A substantiallyl zero changelin cell4 unit volumeas the cleat'vheight, mentioned above, four vother factors vin-y fiuencepcellunit volume variation, when changing from la. straight: t0.,` an, arcuate. course)` These; are: 4wheel:V di:

Vreadily,accessible in the upper A y 6,.thecleatsS4.,pinned to the .cells such Y as 83 inthe outer layer, are very small. As a result, when n the belt '4lipasses over. wheel-14,1the outer. cell 83 inil e3 ameter; the spacing between cleatsgithe spacing .between 'the vinner and outer hinge pins; and the distance along the periphery of each outer cell from one to the other of its outer hinge pins. If the value of one of these factors is changed, a corresponding and compensating alteration must bemade in one or moreV of the other factors. `It vis not possible to providea statement of specific proportions between the factors named whichvwill cover all of the multitudinous combinations possible; it is definitely the case, however, that the relationsY between the factors named must be such as to producesubstantially a zero change in volume as a cell unit,(an innery cell and 'adjoining outer cell) passes on or off a wheel. This statement will suflice, for once madeaware of it, one versed in the art willreadily effect the geometrical manipulations necessary to designation of the correct dimensions, as tothe above-named factors, in a vehicle of a given size. A specific example is readily provided, howeverg'in this, with a cleat altitude of 4 inches, the spacingl'between the apexes of adjoining cleats'is 11 inches and the circumference of the wheels is approximately 55y inches, or the length occupied by ten cleats. The distance lfrom an inner hinge pin 42 (FIGURE 4) to an adjoining outer hinge'pin 47 is 12 inches.

valong the outer portion of the cell periphery, is 26.5 inches. While many variations of the dimensions are possible and feasible, the correct result will not be obtained unless the volume of a cell unit remains, for practical purposes, the same when changing from a straight to an arcuate course. Thus, in'FIGURE 2, the sum of the cross-sectional areas of inner cell 43A and outer cell 44A is the same as the sum of the cross-sectional areas The distance between one n and the other outer hinge 47 of an outer cell, measured of inner cell 43 and outer cell 46. It will be understood l that the two wheels.14, 15 are of the same dimensions, and similar uniformity'exists between the cleats, inner cells, and outer cells.

In FIGURES 2 and 4, a roller is positioned inside each vmounting means and belt tensioning 6 connected to the piston rod of the actuator 102. The other end of the actuator 102 is connected to one arm of another bell crank 212 similarly mounted "on the inboard frame member 20A and having another arm connected to the inboard slider block rod 101. A brace rod 213 iuterconnects the brackets 211, 212. The pivot pins or shafts of the bell cranks 211, 212 mount, in rigid relation to each respective bell crank, Aapair of arms 214, 215 Whose free ends, one extending rearwardlyand the 'other forwardly, are connected by a rod Y216. Hydraulic fluid is admitted under pressure into `the cylinder of actuator 102 through a suitable conduit or'conduits (not shown); extension of the actuator 102-rotates the bell cranks 211, 212 ina direction producing forward motion of the slider blocks 90, v91. Connection of the bell cranks 211, 212 through the rod 216 and-related arms 214, 215 ensures concurrent, equal rotation Vof both belly cranks. The uid pressure in the cylinder of actuator 102 is so controlled as to maintain a desired tension on lthe belt 40,

Ythe control being effected by any conventional, desired means. It will be understood thatsimilar front Wheel means are employed on both ksides of the Vehicle,

The slide support 90, therod 100,v` and the linkage for the actuator 102 are shown lin side view in FIGURE 2.

It will be noted that the edge of the disk 96 adjacent the cylinder 97 has perforations which leave spoke-like supports for the cylinder 97. rThe forward wheel 14, as mounted on the stub shaft 16, serves as an idler pulley variably positioned to maintain the belt 40 under tension. In contrast, the axle 17 on which the wheel 15 is mounted is a drive axle, driving power being-'provided bythe 'eri-l gine 160 (FIGURE l). A drive shaft 105, shown in broken line in FIGURE 2, extends to a transmission 106 for driving the rear axles 17. v

As previously mentioned, the air plenum chamber 33 is closed at its top by the plate.36, at its bottom by the belt 40, and at its sides by the skirt'20 andthe corresponding'inboard'frame member 20A, the chamber ends being closed bycylinders 34 and 35 forming part of variable closure couplings to the respective wheels 14 and 15. As

. best seen in FIGURE A2, the cylinder 34 is mounted on an '40 and which passes through a wall ofa rigid, rectangular tube 73 which extends the width of the belt 40. AS Shown in FIGURE 7, the second roller 75is mountedat the opposite end lof tube 73. Rectanugulartube73 providesfor .lateral support so that the rollers'will transfer to the frame members 20, 20A lateral forces exerted upon the tread 10 vduring maneuvers, Rollers, such as rollers 70 and 75, are provided in each ofthe cleats Von the belt 40 as shown in FIGURE 2. Y v

The belt 40 is maintained under tension by a resilient support for the front wheel 14, vshown in FIGURE 8. rThe axle y16 for wheel 14 is a tubular stub shaft mounted at its outboard end on a slide block 90 in turn mounted in a-slot vSS in the 207A similar slide block 91 operates in slot 89 for mounting the inboard end of the shaft 16. The wheel 14l is providedwith a hollow cylindrical shaft-93 which isv mounted'on shaft'16 bearings 94. The wheel 14'includes a pair of dished plates 95 and l96`securedto suitable hubs on shaft 93 and further secured at their outer peripheries, las by welding,'rto the wheel cylinder 97, the latterbeingl of width corresponding tothe width of the belt 40. The width'of the air cells mounted onl belt 40 is slightly less thanjthewidth of the belt tomaintain clearancebetween the ends of the cells -and lthe `'outboard and inboard frame members 20 and 20A respectively.' The `slide supports 90 and 91 are provided `with'rearwardly extending arms' or rods'100 and 101 v coupled together by alinkagenwhich is actuatedby an y'arm 110 which is hinged to*k anedge of the plenum plate shown) of the frame to urge the cylinder 34 into contact with the wheel 14. Air maintained under pressure inthe plenum 33 aids in the maintenance of ythe seal: between the cylinders 34, 35 and the wheels 14,15. Y i i i The track, constructed and relatedto thel plenum ychamber as described, offers important advantages in 0peration over debris-strewn, dusty, for muddy ground or `oversnow or icef The positive plenum pressure, the downwardly facing orientation oft he plenum chamber, and the close tolerance between the belt and the chamber walls combine tokeepv foreign materialV out ofthe plenum chamber. Encrusted mud, snow, etc. `is naked olf the tread as it changes shape in passing over the wheels;

hence, the tread is eiiicient in self-cleaning. In the lower course, the outer cells press against eachvother'to 4resist the entry of materials between thern,`and such matter as does enter is stopped at the lower hingepins and eject-v ed upon passage over La wheel.

fis-shown in FIGURE 2,y a door 12,0 is famed4 in une yto the platform passage 133.

hand plenum upper bulkhead 36. includes spaced, upper and lower faces 219,` 220 which, in cooperation with the skirt 2l), enclose a chamber 217 opening through a port 134 into the left-hand plenum chamber 33. A similar chamber will 'be seen to be enclosed by the rightfhand plenum plate upper and lower faces and to open through a similar port into the Vright-hand plenum 135. The, plates 219, 220 serve. as structural members which interconnect the skirt 2G andinboard frame member 20A at the lefthand side of thevehicle, a similar construction being employed at the right-hand side.v Meanwhile, structural connection between the left-hand inboard frame member A and the corresponding right-hand member is effected,`

by a central platform or beam 132 with spaced, tight upper and lower plate Vor faces 221, '222 which form anyl airtight passage 133 connecting with the plenum plate passages-'suchas the left-hand passage 217. Close contact or adjacency of the edges of belt to inboard Aand frame members 20, 20A permits air to `be maintained yunder pressure in plenum 33, and similarlyv in plenum 135,

for support of the vehicle.y Drive shaft` conveniently is routed through the platform passage 133. The platform upper'plate 221 forms the hoor of the cargo bay *2.9

(FIGURE 3). It will be notedV that the outlet' of the blower 131 is sealingly connected into an opening leading FIGURE 11 diagrammaticallyshows another view of the-plenum air distributionlsystem. Motor is coupled to blower 131, located in a compartment supplied with blower air by a frame opening 223, the blower output being directed intoplatforrn passage 133 and the latterr ,being connectedinto the plenums through plenum plate l openings 134, 135, As to the track drive system, engine '160,isY shown as connected to transmission 106 -by drive shaft 105. The 4plenum air distribution system above described provides relatively low pressure air for the support ofthe vehicle.

FIGURES '12 and 13 illustrate a system driven from a i secondrairrblower 2R01 mounted on any desired fixed structure 20,0 of vthe .vehicle for providing replacement air, preferably at several times the pressure ofthe airl'from the plenum blower 131, `to the cells ofthe tread. As shownirrFIGURE, l2, a relatively small plenum chamber V is supplied with airby duct171leading vfrom thek blowerrZtll` 1and branching at 171A to a similar plenum (not shown) on the other side of the vehicle. The upjper course ofthe belt 40 passes over the open upper surface of the plenum chamber-170, the ends of which are and seating of'thefplunger38 in the opening of wall 28."

in. a`short-cylinder is secured in the belt k41H0 provide an orifice throughr the belt. A centrally pierced, flexible diaphragm 176'l permits the flow of air through a periphl erally perforated disk. :177, vboth the diaphragm and disc being.n1ountedl inthe Abottom of the cylinder V175, in Vcombination withwhich they form a differential valve means foradmitting airintothe cellsthrough the-belt and for preventing airflow outof the cells throughfthe belt.

Air from-the plenum 170 'may pass upward through the i disk 177 and through the' diaphragm v1576 into cell 180 ofFIGURElZ. If'anyvcell which is connectedto cell 180. ispuncturedl and loses air, the cell willreceive re- 'plenishing airfrom plenumA 170 within each cycle of the Y tread." The plenum 170V is maintained in contact with by springs-V179`mounted on any convenient fixed structure ofthe; frame 23 ofthe vehicle. f

A Where desired,;there is'provlded means for isolation of aigiven cell, cell` uni-t, or gell group uponloss of air -by wall 19 is isolated from the terri. The isolating means is employed as amorliiication yand inthe place of all orpart ofthe intercell oriiice struc- :tures such asV 63,65 (FIGURE 4)..` Any suitable,.so'

called fair fuse o'r equivalent device may be employed between' adjoining cells, a number of such devices being Vgenerally known; and a schematic representation ofone form of isolation device is shown' in FIGURE Y14. A grommet 12 set into `the wallVV 1S of,';for example, an

inner cell receives the tubular end 13 of arvalve .22 VYaf'- i ixed in an opening in an outer-cell wall 19, above which the valve tubular portion. 13 lisincreased in diameter to form a cylindrical casing 24 terminating in an end wall l 26' on which is mounted a'bellows 27 or equivalentdevice whose free end faces kand is separated from the openftubul larend 13 by a partition 28 having a central opening. A rod 37 mounted on the bellows free end extends through the opening ofthe wall 28 and vcarries a plunger j3.8; Vand a spring 39 biases the bellows`2'7 to. an expanded position in which Ithe plunger 38 lies Within the smaller-diameter tubular. portion 13, which isY of slightly` greater diameter the plunger, thecas'e "24 being of still greater 'diameter.Y A bleed opening 47fin ythe bellows free end opens into lthe case 24, and the latter opens' into the outer cell,`formed by wall 19, through openings 48. The annular gapbetween the plunger 38-and tubular end portion 13 is large enough to Apermitmter-cell airflow changes inthe bellows 27 accompanying plunger Vmove-V ments, andthe plunger38 hence remains in theva1ve tubular end portion 13. An `unusually high-rate flowv :may force the plunger 38 into the larger-diameter casingV 24, whereupon furtherrtravel of the plunger ,is stopped. by the increased gap between its Vedge and the leasingand by continued resistance provided yby thebellowsj27'. [If

the outer cell ,or chamber formed by the wallV 19"is ex ,tensively rupturedphowever,V they airflow throughvfthe valve 22 whichV follows is of sufficiently high rate and duration to allow timefor thebleeding of, resisting airl pressure from the bellows through vthe bleed opening 47 Once seated, the plunger 38 is held in place' bythe pressure gradient betweenfits faces, and the chamber Vformed ber formed by wall 18. Y Y

The foregoing-idescriptionof*one embodiment of the present invention-relates to arelatively smalll transport designed for carrying a driver and passenger in thecab andjten` men in the cargo bay. ,By wayV of illustration only, the overall length isof the order vof 17 "feet, the height is 7'1/2 feet tothetop ofthe' fender, andfthe width isabout9 feet. The'- cells operate at aniinternalpressure Aof approximately 2.0 pounds per-'square inch. The pres- Vsure apphed to the ground throughthe treads vis about 1.2 'i pounds per square inch, and theplenum pressure ismain'- I tained ataboutLO'pound per stpaa're` inch. Th'e clearance from theground'to the {bottom} of theplatforrn 132 is `'the lower surface l*ofthe-beItEalOng'its upper coursev by means of *armsv 173, which arms areresiliently supported f it willbeevident that various further modification'sare YV 75 slightly in excess of 2 feet. The vehicle, when operating ln-water, submerges to a Water Vlinezthe; level of-'which Y depends on,the load carried but preferably isl atthebottorn 'of the platform 132,V While'the wheelV disks are shown4 pierced *near` the edges, they Vmay be rmade solid,

thus'permitting sealing of the wheels 14, 15for increased buoyancy; v Y l Y While onlyjonev embodiment ofv the invention; together "i ,withvpossible modifications thereof,has beendescribed detail herein and showntin the accompanyingdrawing,

possible- ,invthe arrangementv andV constructionV offjitsfco'mstill-'inflated inner cham-` ponents without departing from the scope of the invention.

We claim:

1. In a continuous-tread, propelled vehicle; the cornbination which comprises:

longitudinally aligned wheels, one of which may be driven;

an endless belt on said wheels;

structure secured to said belt forming at least one layer of pneumatic chambers;

a downfacing channel between said wheels encompassing the margins of said belt and portions of the ends i of said chambers; and

meansfor maintaining the 4interior of said channel abovel said belt under positive air pressure, said belt being movable perpendicularly to' a lower tangent to said wheels and between said lower tangent and locations thereabove in said downfacing channel.

2. The combination of claim l and further comprising means maintaining air pressure in said pneumatic chambers at a higher value than in said downfacing channel.

3. In a continuous-tread, propelled vehicle, the combination comprising:

longitudinally aligned wheels, at least one of which may be driven;

an endless belt mounted on said wheels, said belt having an inner face contacting said wheels and an outer face;

a plurality of flexible pneumatic chambers attached to the belt outer face and forming at least one layer covering the same;

a downfacing channel between the wheels encompassing the margins of the belt and portions of the chambers, said channel having an upper wall; and

means for maintaining a positive air pressure in the channel between the upper wall Iand the belt, said belt being movable perpendicularly to a lower tan- ,i gent to said wheels and between said lower tangent and locations thereabove in said downfacing channel.

? 4. Ina crawler-type vehicle, the combination which comprises:

a pair of longitudinally spaced cylindricalwheels on each side of said vehicle; belt means linking each said pair of wheels and having a lower course between saidwheels; structure secured to each of said belt means forming 'at least one layer of pneumatic chambers; an open, downfacing plenum chamber extending between each pair of said wheels and encompassing the lower course ofsaid beltmeans for travel through said chamber by said belt means; and means for maintaining positive air pressure in said plenum chamber for pneumatic support of said vehicle above the lower course of said belt means, each of said belt means being movable perpendicularly to a lower tangent to a respective pair of said wheels and between said lower tangentand locations thereabove in a respective one of said plenum chambers. 5. Means for pneumaticl support of a tracked vehicle comprising: I v i v Y longitudinally aligned wheels mounted at the front and rear' of said vehicle; .a flexible, endless belt mounted on and having a bottom course between said wheels; i drive means for one of said'wheels; Y resilient means for urging the other-of said wheels away from said one of said wheels to maintain said belt .in tension; an open, downfacing plenum chamber having.V sides n which intimately confront the edges of said belt along thebottom course thereof; I movably mounted end members for Asaid plenumchamber having means forI engaging said wheels; andv means for maintaining air under positive pressure :within said plenum chamber above the bottom course of said belt for pneumatic support of said vehicle above said belt.

6. Pneumatic support means for a vehicle propelled by endless belt means which is mounted on Vfront and rear wheels and which has a lower course between said wheels, said means comprising: i

exible structure forming a iirst layer of Atransverse air n chambers each extending substantially the width of said belt means;

llexible structure forming a second layer of transverse air chambers secured to said belt means between the chambers of said first layer and bearing against the chambers of the irst layer for forcing the Alatter against the belt means;

an open, downfacing plenum structure having an upper wall spaced above a lower tangent to said wheels and downwardly extending sides for 'engaging opposite edges of said belt means for maintaining lat a minimum the clearance between said sides and said edges; and

means for maintaining air under pressure between said plenum structure and the bottom course of said belt means for pneumatic support of said vehicle above said belt means.

7. The combination set forth in claim 6 in which a cross-stay means extends through the interior and between the ends of each said chamber.

8. The combination set forth in claim 6 in which each chamber in said rst layer is of doubly truncated triangu- 'lar cross-section with one side thereof contiguous to said belt.

9. The combination set forth in claim 6 in which the chambers in said first layer are of doubly truncated triangular cross-section with one sidethereof contiguous to said belt and the other two sides each contiguous to one of a pair of adjacent chambers in said second layer.

l0. The combination set forth in claim 6 in which each chamber of said second layer has two side walls contiguous with side walls of chambers in said first layer and an arcuate, outer tread face. f

11. The combination set forth in claim 6 in which each chamber in said first layer is of doubly truncated isosceles triangular cross-section with the base thereof contiguous lto said beltA and in which each'chamber inthe second layer Vhas two side walls contiguous with side walls of chambers in said first layer and an arcuate, outertread face'.V

12. Pneumatic support means for a vehicle propelled by endless belt means which is mounted on front and rear wheels and which has a lower course between said wheels,

Aflexible structure forming a second layer of transverse I air chambers secured to said belt means between the chambers of said rst layer and bearing against the chambers of the rst layer for forcing the latter against the belt means;

an open, downfacing plenum Astructure having an upper wall spaced above a lower tangent to said wheels and downwardly extending sidesY for engaging opposite edges of said belt means` for maintaining at a minimum the clearance between said sides and said edges; means for maintaining air under pressure between said plenum structure and the bottom course of said belt means for pneumatic support of said'fvehicle above said belt means; and v structure forming flow channels of limited ow capacity through the contiguous walls of adjacent pairs of said chambers where oneichamber of each pair'is in said rst layer and one is in said second layer. Y 13. The combination set forthin claim l2 wherein said structure forming flow channels oflimited flow capacity interconnects said cells to form a plurality of separate groups ofsaid cells., f

' atlat belt;

14. lThe combination set forth in claim 12, wherein ity interconnects adjoining ones of said chambers in isolated groups wherein the length of any group 'along said'belt means is less than about one-half the peripheral length of said belt means.

15. A pneumatic track for an endless-track propelled vehicle which comprises;

resilient structures extending transversely of said belt forming an inner layer of chambers of doubly A truncated triangular cross-section the bases of which are contiguous to said belt; and resilient structures extending transversely ofsaidbelt forming an outer layer of chambers each having a first Wall contiguous to a lirst chamber in'said inner layer and a second wall contiguous to a secondchamber in said inner layer yadjacent to said first chamber. 16. -A vehicle propelled on a pair of endless pneumatic tracks which comprises:

a chassis having transverse axles at one end and a pair of stub shafts at the other end; l a pair of cylindricalwheels mounted onsaid axles on opposite sides of said chassis;

a cylindrical wheel mounted on each of said stub shafts' iiexible structures secured to each offsaid belts and interleaved with the'chambers ofsaid iirst layer to form a second layer of transverse chambers; and p structure associated with the chambersof each belt and formi-ngi flow channels of limited ilow capacity through the contiguous walls of adjacent pairs of said chambers where onel chamber-of each pair is in Ysaid Vfirst layer andorre isin'said second layer.

l7. In a vehicle having spacedcylindrical wheels `and anr endless belt'krmounted on said wheels for travelling straight upper and lowerV courses therebetween and a semicircular, larcuate course over eachwheel, a tread for said belt comprising: Y v Y j contiguous, flexible, inflated inner chambers-forming a Y first layer on theV belt and of doubly truncated `triangular cross-section, each with its base against Vthe belt and each having an apex, a Space ofisosceles triangular cross-section` and extending across Vthe belt interlying each adjacent pair of inner chambers; spaced, flexible cleatseach attached on and yhaving any apex spaced from the belt in airespective one of v said spaces and having two Walls forming equal sides of an isosceles triangle and each lying against aref spective one ofV a respective Ypairy ofinner chambers;

Y contiguous, llexible, inflated outer chambers forming an out'e`r`,second layer von thebelt and each having an apex contiguous with a corresponding cleat apex and a pair of sidewalls each contiguous witha respective inner chamber and coming-into contact witha sidev `wallpof Van adjoining outer. chamber at a locationlying'outwardly of the belt from and in register with the apex'` ofa respective inner chamber, each outer chamber thus having two or said locationsof'contactand further having kan outer tread. wall portion extending between said locations;

- i inner iattaching means pivotally yjoining each outer,

chamber apex-to a respective cleat apex;

outer attachingmeans v/pivot'allyijoiningeachouterY chambertodwov adjoining outer chambjersxatsaid locations of Contact,

Y' the :spacing-of the cleat apexes from .the belt and each 18. In a continuous tread propelled vehicle, `the combination which comprises: n, Y.

an endless track and a pair of support` and drive wheels therefor; j structure secured to said track forming a pair ofinterleaved layersk of transverser pneumatic chambers;

a downfacing channel between saidwheels encompassing the margins of said track alonga lowerrcourse thereof lbetween said wheels for support of said vehicle;

and supply `means between saidwheels'cont-acting said track as it passes along the upper course thereof for introduction of air into said chambers. as they pass said supply means. Y' 19. In a continuous tread propelled vehicle, the combination which comprises: f

longitudinallyvaligned wheels one ofy which is driven; an endless' track on said wheels; v structure secured to said track forming a pair. oflayers of pneumatic chambers;

differential'valve means extending zthrough said'track at a plurality of longitudinally spaced points'to' form now paths through said track 'into selected ones of said chambers; j upfacing channel means supported between said wheels for contacting .said trackfor successive registration with said valve'means; and means for supplying air to saidlupfacing channelr'neans at a pressure atleast equal tothe pressure normally to'be maintained in said chambers' for maintaining n air in saidV chambers at a predetermiued'pressure.'

20. In a continuous Vtread propelledY ve'hicl'e,'the "combination'whichv comprises: l Y

longitudinally'aligned-wheels one of whichl mayfbe driven;

an endless belt, mountedv on pand lhaving upper and lowercourses extending between'saidvwheels;

^ structure secured to said belt forming inner and outer layers of pneumatic chambers;

a downfacing channel vbetween said wheelsencompass'- ing the margins of the lower courses of said belts;

an'upfacing channel between said wheelsl adjacent toV tive pressure with the air of the upfacing channel at la pressure in excess of ythe pressure of the airl i'n thekv downfacing channel. x f Y Y; l21. Pneumatic support means for-a vehicle propelled by endless belt means which is mounted on front andrear wheels and which has a lower course'b'etween said wheels,

j said means comprisingi s ,Y

exible structureforminga' first layer of transverse air chambers each extending substantiallyjthe Vwidth of said beltlmeans;Y v Y 1 flexible structureforming a second layer of traiisverseY .f `air chambers secured to said belt means'between the chambers ofsaidtirs't layer. and` bearingV against the.,

chambers of" the. iirst'layer` for `forcingtlie latter against the belt-rneansgvY-jV l meansfor maintaining air insaid channelsunder posi` an open, downfacing plenum structure having an upper Wall spaced above a lower tangent to said wheels and downwardly extending sides for engaging opposite edges of said :belt means for maintaining at a minimum the clearance between said sides and said edges;

means for maintaining air under pressure between said plenum structure and the bottom course of said belt means for pneumatic support of said .vehicle above said belt means;

structure forming ow channels of limited flow capacity through the contiguous walls of adjacent pairs of said chamber where one chamber of each pair is in said first layer and one is inrsaid second-layer;

means for introducing air into the chambers of the irst 15 layer for maintaining van air pressure within said chambers of the irst and `second layers which is 14 higher than the air pressure within the downfacing plenum structure; and flow-responsive valve means interposed in at least some of said flow channels through the contiguous walls of adjacent pairs of said chambers for allowing normal f flow between adjacent pairs of the chambers and for cutting olf liow between said chambers when the flow becomes excessive.

References Cited in the le of this patent UNITED STATES PATENTS 809,048 Furchtbar Ian. 2, 1906 2,713,521 Curtis July 19, 1955 2,900,210 Parsons Aug. 1S, 1959 3,074,764 Bertelsen Ian. 22, 1963 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTICN Patent No. 3,170,533 February Z3, 1965 Kenneth J. lPewel et a1.

1t is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 14, for "three-Stag" read three-stage Column 6, line 60, for "oft he" read of the column 7, line 15, for "plate" read plates Column 11, line 67, for "or" read of Signed and sealed this 27th day of July 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attvsting Officer Commissioner of Patents 

16. A VEHICLE PROPELLED ON A PAIR OF ENDLESS PNEUMATIC TRACKS WHICH COMPRISES: A CHASSIS HAVING TRANSVERSE AXLES AT ONE END AND A PAIR OF STUB SHAFTS AT THE OTHER END; A PAIR OF CYLINDRICAL WHEELS MOUNTED ON SAID AXLES ON OPPOSITE SIDES OF SAID CHASSIS; A CYLINDRICAL WHEEL MOUNTED ON EACH OF SAID STUB SHAFTS AND EACH ALIGNED WITH ONE OF SAID WHEELS ON SAID AXLES; MEANS FOR DRIVING SAID AXLES; A FLEXIBLE BELT ENCIRCLING THE WHEELS ON EACH SIDE OF SAID CHASSIS; RESILIENT MEANS URGING SAID STUB SHAFTS AWAY FROM SAID AXLES INDEPENDENTLY OF EACH OTHER TO INDEPENDENTLY TENSION EACH OF SAID BELTS; FLEXIBLE STRUCTURES POSITIONED ADJACENT EACH OF SAID BELTS AND FORMING A FIRST LAYER OF TRANSVERSE CHAMBERS AND FLEXIBLE STRUCTURES SECURED TO EACH OF SAID BELTS AND INTERLEAVED WITH THE CHAMBERS OF SAID FIRST LAYER TO FORM A SECOND LAYER OF TRANSVERSE CHAMBERS; AND STRUCTURE ASSOCIATED WITH THE CHAMBERS OF EACH BELT AND FORMING FLOW CHANNELS OF LIMITED FLOW CAPACITY THROUGH THE CONTIGUOUS WALLS OF ADJACENT PAIRS OF SAID CHAMBERS WHERE ONE CHAMBER OF EACH PAIR IS IN SAID FIRST LAYER AND ONE IS IN SAID SECOND LAYER. 